TIL experimental Thorium nuclear fission isn't only more efficient, less rare than Uranium, and with pebble-bed technology is a "walk-away" (or almost 100% meltdown proof) reactor; it cannot be weaponized making it the most efficiant fuel source in the world

I must say, something in here makes me assume that this isn't something you learned today.

On a side note, Thorium isn't a miracle fuel, it can be weaponized, it is more complicated and more expensive to use, and it can not function in non-breeder reactors. (Well, it can work if you mix it with standard uranium)

The passively safe advantage of pebble beds is independent of fuel source.

If you pull out the protactinium-233 early in the reaction stage. The thorium will not produce uranium-232. This is what makes thorium decay dangerous. But the protactinium-233 will decay into pretty pure uranium-233. Which can be used in place of plutonium for nuclear warheads.

Thorium has its share of risks as a nuclear fuel, and it isn't obvious that it would be a significant improvement over uranium in terms of safety, proliferation prevention, or cost. If an easy-to-switch-off accelerator is used to supply neutrons, and a molten salt reactor is used, then some (though not all) of the main failure modes of uranium reactors could become less likely, but at the cost of developing new technology and constructing new facilities, while also risking hard-to-detect proliferation. If India or the other nations considering thorium do develop thorium reactors, they should be aware of the risks that come with the new technology, and the the additional vigilance that would be needed to minimize nuclear proliferation by way of thorium.

One of the major reasons it cant be weaponized is that the uranium it breeds is so damn radioactive that it is really hard to fabricate the bomb elements without killing yourself. Terrorists dont like to waste what few nuclear engineers they have. Not to mention every geiger counter in the area will be going off so its not exactly subtle.

Only a rogue country could have resources for this, and even then, it would be easier for them to use a traditional breeder system for that (less likely of killing all their engineers and scientists)

I don't think terrorism is the main fear that prompts un-weaponisable reactors. If terrorists are getting into nuclear reactors, the least of our worries is them walking out with materials to build a bomb. The fear is mainly governments using them to construct nuclear weapons. For example, if we made sure countries such as Iraq used only thorium reactors, there would be (pretty much) no worries that they might be using it as a cover to build weapons.

The part above kicks in. It is easier to use existing techniques to make nuclear weapons versus thorium fuel cycle. You still have the handling and containment problems. Not to mention it may have the demon core problem of going critical at the smallest force. A little boy style weapon is easy compared to that.

Guess we would know when some dictator has to explain why his underground research base blew up, evasive he was experimenting with nuclear weapons.

Its still hideously radioactive. To the point your bomber would be dead from radiation poisoning long before he got to his targets location. That and every geiger counter in the ports and motorways will be going off like crazy (as it would take a truck to transport enough shielding for the bomber to not drop dead of radiation poisoning in an hour. Hard to get your jihadist on when you start vomiting your guts up after 10 minutes of exposure. The lead shielding still wouldnt stop some of the radiation emission)

Seems easier to use neutron activation (ala radiactive boyscout) on uranium ore, or use biological or chemical weapons.

A u233 dirty bomb seems convoluted, expensive, and hard to actually weaponize without killing your own people (valuable people, not grunts). Much easier ways to make dirty bombs.

While constantly getting bickered by random "geek" support (in most cases Otacon) via voicecomm and having an internal revelation of what it really means being a soldier and sacrificing yourself for your country.

Hard to say. We really have no idea how expensive traditional nuclear energy is because we haven't disposed of any of the waste yet. Really, we haven't finished paying for the first kilowatt hour. It might prove to be prohibitively expensive once we get around to actually doing something about it.

Edit: My phone changed "disposed" to "exposed". I can't edit on my phone so I had to finish pooping before I could fix it.

WHAT? A SIMPLE SOLUTION ALL THESE GENIUSES HAVE OVERLOOKED AFTER ALL THESE YEARS??????

(seriously, when morons say "all you have to do is...." to a complicated problem, my standard response is that if such a solution existed, it would have been tried already, because smarter people than you and I have put much more time into thinking about the problem)

That's what happens when the media portrays smart people as being dorks and completely out of it. You get these people who entirely disregard smart people and instead mock them and claim they're useless. You get people like this:

Some people are really attracted to seemingly simple solutions to intractable, complex problems. Everybody wants a deus ex machina, and everyone wants to be one of the smart people who gets to scoff at all the rest of the world who can't see the "solution" right in front of their faces.

Thorium true-believers in particular, and nuclear true-believers in general are some of the worst offenders in the energy world. Many of them see only the promise and none of the drawbacks, challenges, or risks. They aren't alone, of course. There are plenty of dilettante renewable supporters who talk like all you have to do is put PV on every rooftop and then its all good (it isn't). I at least appreciate that both sets recognize that there is something deeply problematic and unsustainable about the status quo, which is in contrast to the fossil-fuel defenders who just have their heads in the sand.

These misconceptions are absolutely bizarre. Assuming people have read them, I'll deal with them in order.

A) Those are the reasons given, which are untrustworthy at best, and still B) "MSR shouldn't be followed through with because we're already a few years into the LWR industry, which was designed by the same man who then went on to say we should move on to MSRs?" Terrible reasoning.

The author openly admits it IS true that they don't need enrichment - listen, when people are touting something like this they'll say shit like "it's green" as well, which doesn't mean they're saying other forms of energy production aren't green, but that that's DEFINITELY a big tick for thorium MSRs.

The U-233 and 232 that are produced during the thorium fuel cycle are not denied or hidden by the proponents of the technology. They point out deliberately that the high gamma radiation of the isotopes make it so problematic for would be terrorists to obtain that the mildest form of security protocol around the issue would be sufficient for a government to protect against its misuse. It is proliferation resistant, not proliferation proof.

So many things. A) the author admits there is more thorium in the continental crust and in the moon and various asteroids than uranium. B) He admits it is easier to obtain these elements from a continental crust than the ocean. C) He tries to show that uranium is more abundant in the ocean than thorium, like those previous two points are just wiped away by that fact, a fact which is based on a very regularly unreliable thing to analyse in total, the ocean. D) Having more of an element IS IMPORTANT. Jesus Christ, what the hell is he talking about trying to dispute that.

As before, just because there are other techs in town which can achieve the same things as thorium does not mean the thorium MSR should be dismissed. Hell, there are multiple thorium based reactors, not just MSR. Imagine if someone went "Well hell, a thorium MSR isn't the only reactor that uses thorium (which is really abundant and therefore a desirable attribute), there are thorium LWRs as well, so thorium MSRs aren't special at all." That's a brick wall of an argument.

This isn't even deriding thorium MSRs, it's just saying there are different toys you can play with that use thorium. It even says that MSRs are a really good idea.

The article isn't anti-MSR in the least. The institution that wrote it is adamantly pro-MSR and pro-Thorium, as stated in the introduction of the article. Some fringe parts of the pro-Thorium community were getting a little out of hand with their over-promising, so these misconceptions were identified to bring everyone back down to Earth. Anyway, to counter:

So do you think that an unreferenced statement about weaponization is more credible than AEC documents from the time? For B), where is that said? This article fully supports the further development and construction of a fleet of T-MSRs.

It's a misconception. Sometimes people claim that T-MSRs are the only game in town that don't need enrichment. If you already know that this is not true, then that's great! This article is for people who are less informed than you on the issues, or who are being actively misled.

The articled that OP linked seems to disagree with your statement and that's why this misconception exists and is treated.

The author does not admit that it's easier to obtain these elements from the crust. Quite the opposite! Since the ocean delivers, it's conceivably much easier. Anyway the point is that it doesn't matter because no one is going to run low on Th or U with breeder reactors in the meaningful future.

Again, it's for people who don't understand the nuances as intricately as you do. The whole webpage assumes no prior knowledge of nuclear issues. If you read the super pro-MSR stuff, you might believe that MSRs are the only game in town. Again, if you already know better, then that's great!

Of course it's not deriding MSRs. The whole article and webpage is pro-MSR. Did you see the companion article?

The U-233 and 232 that are produced during the thorium fuel cycle are not denied or hidden by the proponents of the technology. They point out deliberately that the high gamma radiation of the isotopes make it so problematic for would be terrorists to obtain that the mildest form of security protocol around the issue would be sufficient for a government to protect against its misuse. It is proliferation resistant, not proliferation proof.

This used to be true, but some clever engineering maybe two years back (actually a really simple approach) demonstrated that this U-232 contamination obstacle to proliferation was easily overcome. As far as proliferation risks go, MSRs must be treated no different than other reactor designs.

And I don't get why not being able to weaponise it makes it more efficient. Surely multifunctionality extracts the maximum benefit from the technology: when you've finished powering your country, you can hurl it from a giant trebuchet at the country next door, or whatever.

What makes it more efficient is that (some) thorium reactors don't require as big of a containment system, can't meltdown, and they don't produce nearly as many long lived radionuclides as waste products.

Did anyone else notice that this is a 5 year old article and the fact that it lists uranium as being in dangerously short supply says alot about the quality of the article.

The author of the article A. Canon Bryan, lists himself the CEO of a company called New Energy Metals Corporation which has no google listing at all. His LinkedIn profile, on the other hand, lists him as the CEO of a company called Vico Uranium Corp a company founded in 2010, a year after the article, to develop and exploit uranium deposits.

So far, it seems that only India have started working on any reactors.

Yeah. Thorium is massively, massively more expensive than uranium. Elemental abundances don't tell you anything about mining and refining difficultues.

With regards to the pebble bed reactor and it's 'safety', if the cooling system fails (as happened in Fukushima), the decay heat of the reactor will melt the fuel and pop those silly stupid graphite balls with the vapour pressure. It doesn't matter that overheating shuts down the reactor - the decay heat continues. And when air gets in, the graphite will burn and you'll get second Chernobyl in place of what would have been Fukushima otherwise.

edit: source on the cost disparity for those afflicted with the thorium hype: http://www.thorium.tv/en/thorium_costs/thorium_costs.php . Even this pro thorium source has to acknowledge that thorium costs 5000$/kg and uranium costs 40$/kg (before handwaving of how the price should drop to $10/kg just because it's 4x more abundant). Ultimately, all those "thorium" breeder reactor designs - including the molten salt ones - are capable of using natural or even depleted uranium (of which there's a ridiculously huge stockpile), and as such there's no rationale to waste money on setting up massive thorium mining. Likewise, thorium reactors are capable of producing plutonium by irradiating uranium inserts, hence they still present a nuclear proliferation risk. Some folks bought thorium mine stocks, ran stories in media, sold off the stock on the peak, that was pretty much the whole story with thorium. Ohh, yeah, and some experimental reactors were built for science sake.

IIRC it is extremely unlikely that Thorium would cause a meltdown, let alone an incident similar to chernobyl and fukushima. One of the main reason people want to push Thorium reactors is because it is, to my understanding, deemed a lot safer.

Thorium is a waste product of rare earth mines, which we need for all those nice solar panels, wind turbines, and electric cars. The U.S. has shut down all its rare earth mines in part because miners don't want to deal with thorium disposal.

The reactor people are excited about is not the pebble bed, it's another design with liquid fuel. If the cooling system fails, a frozen plug at the bottom will melt and all the fuel will dump into a tank designed to passively cool it. There won't be much decay heat, because with liquid fuel all the fission products that produce decay heat can be continuously filtered out.

And yet between the greens and the publics uneducated perception of nuclear energy (a couple of the key anti-nuclear protestors around the world are Australian :/) we'll never have a reactor of any kind apart from Lucas heights research facility... The rest of the world will just end up buying it off us...

I think the point is that this system, if it is the one I am thinking of, does not need power to be meltdown proof. Unlike Fukushima for example, where generators were needed for cooling, this works in an opposite fashion where a cut off of power leads to all sorts of safety protocols instead of an "Well shit" scenario.

Because the unthinkable happened. They do have those now (or will soon). In the US, the industry is implementing a system where 2 regional stations (Memphis and Phoenix I believe) have readily available emergency equipment (pumps, generators, etc.) in case of a Fukushima like situation. The components can be flown/driven in to supply emergency functions within days.

The safety features worked exactly as designed - it was designed to cope with a huge earthquake and giant tsunami of a certain height, but the one that hit was bigger than its design spec, flooding the complex.

Essentially, in engineering you want to have backups for the backups, so that you can have multiple levels of redundancy.

In this case, the earthquake did damage to the primary systems, but then a fucking tsunami came in and took out the redundancies. It's kind of like being in a flood and then being hit by a tornado. Your systems can handle one disaster but 2 disasters is incredibly unlikely. Unfortunately for Fukishima, they got hit by two big disasters that were triggered by the same events.

Fukushima had 10 meter seawalls, and they got hit by 13 meter waves. They didn't have bigger seawalls because based on historical data, the 10 meters was already overkill. I believe the biggest that area had been hit with before was 6 meter waves.

There's a major difference between the LFTR design that most Thorium advocates propose and the old high-pressure desings that are most common today. Read up on LFTR and you will see that it really is much, much more fool-proof safety-wise.

It's not impossible, but the main design is supposed to allow for passive cooling. This means there needs to be no human interaction what so ever for the fuel to be pulled from the reactor into a cooling chamber.

With current reactors, you have to insert control rods the more or less fuck up the chain-reactions of nuclear fission, but the fuel is still incredibly hot, requiring days worth of water cycling to cool it down. If pumps aren't operating, the fuel heat isn't dissipated, and it melts through the tube housing and well, "melts down" until it gives off all the extra heat. often going through steel and even concrete before it finally cools off. And THAT leaves a radiation signature that's lethal to clean up (see the infamous "elephant foot" of Chernobyl).

The idea of an LFTR is that a salt plug will be refrigerated at the bottom of the reactor tank, which under a power failure, will melt and drain the reaction tank into a long, flat cooling tank where the fuel will spread out, giving it loads of surface area to dump off the extra heat rapidly. The lower density of radioactive elements in the fuel means the cooled, crystallized fuel mix can be re-harvested and placed back into the reactor, once everything is back up and running.

The problem with the freeze-plug is that it takes a long long time to melt (say 15 minutes according to Japanese research). In the event of a temperature excursion you have your freeze plug at the bottom of the core, which is thermodynamically likely to be the coolest point. You then would have fuel at the top of the core hotter than it should be and getting hotter (if it's graphite moderated there's a slight positive thermal void coefficient). This shouldn't be a massive problem, except that the only alloy we'd presently use for an MSR (mod. Hast N) only has about a 50C margin between it's melt-point and the predicted outlet temp of an MSR when you consider the required efficiency and the melt-point of the salt. There's a reasonable change (huge actually in nuclear terms) that you'd melt your vessel before the freeze plug operated.

Using what for power in the meantime?
Nuclear is cleaner than the dirty fuel sources many nations are turning to, and using it does not pump co2 into the atmosphere.
That being said I am a fan of CANDU reactors, so thorium is not high on my list.

I agree. Gen 3+ reactors like CANDUs are plenty good for right now and have only just started to be deployed. There is no reason to invest in a whole new fuel system and the infrastructure behind it right now especially with all the political and societal opposition that already exists surrounding fission. Reddit seems to think thorium is some magical thing that is ready to be deployed right away, but due to some conspiracy is being kept from the energy market. The truth is that it isn't. There are still plenty of engineering problems surrounding Thorium especially with things like LFTRs, and it would require a completely different fuel cycle which would have a different manufacturing process than our current one requiring further investments and changes.

Got to throw my tidbit in here about uranium not being easy to weaponize. If I wasn't hungover I could remember the numbers on the uranium but look it up. Its not as easy as the media made you believe.

The nuclear reactors we have today were built to use and provide weapons-grade fuels because they were needed to build massive stockpiles of nuclear weapons, particularly in the US and France. There was no investment in other fuels or reactor types because they were not useful in building nuclear warheads.

I suppose for a very cheap, rough-and-ready system that could work to generate power. PV cells are far more efficient, though. PV is about 20% efficient in a high-end panel whereas steam engines alone are about 3-5% efficient. Plus, the steam engine would require extra space that would not be used for gathering more sunlight.

Because most of the world doesn't have enough direct/strong sunlight to make it viable, since in the UK for example, you would need huge fields of mirrors to get any real benefit, and it costs too much, for too little gain.

These plants are generating power on par with medium sized fossil and nuclear plants, but take up a mindbogglingly huge amount of space. These mirrors must be cleaned regularly, as dust significantly impacts the amount of sunlight reflected, and, of course, they have to track the sun in the sky to maintain focus on the tower, meaning eachof them has incredibly accurate motors and actuators to correctly position the mirror every day. This all adds up to say maintenance costs are insane compared to traditional power supply methods (but the fuel, of course, is free!)

Effectively, to utilize solar-thermal power, you need to have vast swaths of land where no one is making a living. Which makes for a kind of crappy place to put a power plant, as it's nowhere near anyone who'd want to use the power.

Anything highly radioactive can be weaponized. It may not easily be made to generate enormous nuclear explosions, but all you have to do is spread some around a few city centers and millions would die.

Much of America's prosperity came to us because energy was cheap and abundant. Cheap food and cheap energy gave big economic edge, and a large middle class. Thorium technology is not new. The reasons why we moved away from it were political, not technical. Thorium still offers the possibility of cheap abundance again. We have stockpiles of thorium buried in the desert in Nevada. It is a waste byproduct from mining rare earth metals that we need for so much new electric based technology, that we currently depend on China for. At this time, when income inequality is at it highest since the last depression, I have to wonder. If the people actually had any real political power, wouldn't thorium reactors be a higher priority?

The sad thing is most people brought up in the cold war era a very anti nuclear. While I'm all for these it might be decades before they are actually being built. It's weird that we have a viable energy source at the tips of our fingers but people are afraid to use them.

Let's amend that to say that the Cold War has nothing to so with fear of nuclear power per se (since that is when nuclear power flourished), but that the fear in the US preventing any further development of nuclear energy in the US began with Three Mile Island, deepened with Chernobyl, and now solidified with Fukushima.

The companies that make the wildly expensive uranium fuel rod assemblies, that go in current nuclear reactors...at the moment...have enough juice in Washington to derail any real effort to develop Thorium power in the U.S. So we will lose out to China, India, Europe, etc., all because of greed.